Apparently, Jimmy Leeward made unapproved mods , and failed to perform 3+ required hours of flight testing.
There was a structural failure of the trim tab on the horizontal stab caused by old nuts being used, which resulted in flutter and loss of control. It pulled 17 G's in the pullup..There is evidence of the fuselage twisting so badly the canopy no longer fit properly, it "oilcanned".

For those of you who are the engineering types, the accident report makes for some very interesting reading as well. Considering how little of the airplane was left, it is amazing that there are able to piece together such a detailed report. The one thing which the report failed to note was the wrinkling visible on the upper wing skins in several of the photos. Also, the fact that the plane stayed mostly in one piece after a 17G upset is quite remarkable.

I would imagine that the wrinkling is the result of an overload, so I am assuming during the 17g pullout. I have only scan read the report, but will take a closer look when I get a chance.

You need to keep in mind that wrinkling is not necessarily an indication of an overload and permanent deformation, in the case of the fuselage, it appears that the wrinkling went away when the plane was not being flown. It could be a similar situation with the wing. It would be interesting to see if the wrinkling on the fuselage was in opposite directions when viewed from the left or the right. If that were the case, it would probably indicate a twisting load, maybe due to the elevator only having a single trim tab on the left side.

What I find surprising is that the pilot continued to fly even after there was enough deformation for a gap to exist along the canopy seal. At those speeds it seems to me that you would notice the onrush or air or the additional noise.

I remember reading a detailed account in a book on the Me163 Komet about a P51 pilot who followed an Me163 into a dive in an attempt to shoot the plane down.
The American pilot ended up returning to his airfield but needed help to exit the aircraft, the report said that he seemed exhausted and disillusioned. The report said that the ground crew were astounded to see that the covering on the P51's wings had become rippled like an even swell on an ocean and remained like it. Reading this it sounds like that pilot was lucky to get away with it all those years ago.

Managed to re-read the report last night and it appears to indicate that the team had a somewhat loose approach to things; flight logs did not match reported flight time, the pilot under reporting his age, significant changes to the mass balances and an apparent change in the tone of the airplane at speeds above 400 knots. The later one was probably the biggest clue that something was not quite right.

hi, some of aircraft was reskinned whith thinner aluminum .back when he was on
here they were discussing use of telemtery device and its sensors to check
how the thinner skins were handling loads.also the use of thin layer of foam on inside of
wing skins to to help prevent wrinkling. was interesting .

Could you provide a link to the discussion you mentioned? I would be curios to read it. Although I not an aerospace engineer, I believe that a lot of times the thickness of the skins is determined by trying to avoid handling damage rather than flight loads. That seems completely feasible. However, it appears to me that the MKII eyeball would have sufficed to detect the wrinkling given that they show up in the photos quite well.

If I remember, P51's had two ele trim tabs, and they removed one.
With the speeds being achieved, the bird would really be wanting to climb, and significant down trim would probably be needed. I suspect when the faulty nuts and hardware let go on the trim tab, it caused that 17G pitchup, resulting in a blackout (or death) of Mr Leeward. He is not seen in the cockpit in any vids....
After these findings, I am surprised they were able to get insurance enough to run this years races!
Mark

The tail wheel extended due to the 17g upset. The report stated that the pilot probably lost conciousness within 1sec or so. He did not feel a thing; however, the same cannot be said for those on the ground, 64 injured and 10 deaths. That is what truly makes this tragic.

A tragedy indeed.
17G upset, you think? Sort of like saying the aircraft disintegrated because of the impact with the ground...
Something must have failed in the mechanism to cause it to fall open like that.